My truck failed TX inspection, the HC was a little high. Im not completely surprised, ive had this ongoing problem of the truck pinging a lot. I have to put 93 octane in it, and i still get a little pinging going down the highway. I even pulled the timing back to 6 or 7 degrees. In a post a couple months ago, it was suggested that i plug the AIR ports on the back of the head, I did that and it helped, a little. Things that i have replaced in the past year: o2 sensor, distributor, spark plugs, fuel pumps, pressure regulator, TPS, ECT. the cat is only a couple years old.
The only thing that is left is the injectors. I think that there are a couple that are running too rich and causing the other cylinders to lean out, or vise versa. What do you think? btw no codes, although sometimes if i put a lower octane gas in i will periodically get a code for o2 sensor always lean.

 

Did you run both the KOEO and KOER test?

 

I don't see how the octane of the fuel would give an O2 sensor code.

Something you could do is try to get it to pass with 87 octane in it. Was it close to passing?

What year is the truck and what engine?